Scottish and Southern Energy has added 650,000 customers in the nine months to December 31.

In a trading update the company said it now had 8.4 million customers making it the second biggest provider of gas and electricity in the UK.

The acquisition of Airtricity, for around £1.1billion, is also on course to be completed by the end of February.

Chief executive Ian Marchant said:

"At the start of this financial year, we said SSE's asset base was expanding significantly through investment, and that the value created by this would be complemented by value enhancement from operational excellence.

"We also said that we would seek to create value for shareholders through acquisitions, if they were compatible with our financial principles. We have made major progress in our operational and investment activity."